System and Method for Solar Powered Thermal Management and Transport

ABSTRACT

A refrigeration system for vaccine storage and/or transportation includes an inner chassis. One or more vertical lift carriages are positioned in the inner chassis and can house a plurality of vaccines, pharmaceuticals, and/or other perishable items. Each vertical lift carriage is contained in an isothermal chamber. One or more isothermal chambers surround a phase change reservoir (PCR), which is positioned at a central location of the inner chassis and contains frozen water or another phase change material. A thermal attenuation layer can be disposed between the PCR and each isothermal chamber to moderate energy transfer between the chamber and the PCR, thereby controlling the temperature range in each isothermal chamber. Methods for making and using the refrigeration system are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/909,314, filed Nov. 26, 2013, the disclosure of which is herebyincorporated by reference in its entirety and for all purposes.

GOVERNMENT LICENSE RIGHTS

This invention was made with government support under Contract No.DE-AC02-05CH11231 awarded by U.S. Department of Energy. The governmenthas certain rights in the invention.

FIELD

Embodiments are directed to thermal and data management systems andmethods, and more specifically, but not exclusively, to a system andmethod for providing scalable and intrinsic solar powered refrigerationfor transportation and remote delivery of vaccines, pharmaceuticals, andother perishable items.

BACKGROUND

The World Health Organization (WHO) estimates that, globally, close totwo million preventable deaths each year occur due to lack ofimmunizations in children under five. Thirty million children—roughlyone in five born each year—globally remain unimmunized orunder-immunized, and are at risk for vaccine-preventable communicablediseases that can cause debilitating and incapacitating healthconditions or fatality.

Vaccines are highly sensitive biological materials that require strictstorage and maintenance standards. For example, vaccines need to bestored in a very narrow temperature range (e.g., 2-8° C.) throughouttheir life to preserve their viability. Storing vaccines at impropertemperatures can destroy the vaccines' viability and is one of thegreatest unsolved problems faced in the vaccine cold chain in developingcountries. Globally, half of vaccines are wasted, in large part due totemperature excursions beyond the aforementioned temperature range.Further, under-immunization is not due to high vaccine prices, butrather to breakdowns in the supply cold chain. Current solutions attemptto increase capacity and frequency of vaccine distribution from nationalsource locations where infrastructure is sound.

However, despite the sound infrastructure at the national sourcelocations, the other parts of the supply and distribution network indeveloping countries face serious infrastructure challenges (especiallypower and transportation) and are hard to reach. In an illustrativescenario, the first stop in distribution from the national sourcelocation would typically be to a regional store, which serves a largeportion of the country. Often, there are fewer than ten regional storesin, for example, a mid-sized sub-Saharan African Country.

From the regional store, vaccines move to a District Store, wherevaccines typically are stored for onward distribution to one or moreremote places. District Stores unfortunately are equipped withinadequate power infrastructures and have only intermittent electricity.Power outages can result in storage temperatures exceeding theacceptable temperature range for vaccines. This exposure to heat canrender vaccines ineffective.

A selected District Store may supply several “Health Centers,” whichoften are located in remote locations and similarly face intermittent,or no, electricity. Furthermore, outreach includes day-long trips byhealth workers to the most remote areas that are not in close reach ofhealth centers. Locations served by outreach are often the areas wherevaccines are most needed, because these locations have the least accessto healthcare. These areas typically are the least developed in the colddistribution chain. Delivery of vaccines to these remote places requirespotentially several miles or days of walking (or bicycle) transportationduring which there are few ways available to maintain the viabletemperature range for the vaccines. The segment of the cold chain fromhealth centers to outreach, particularly in rural areas, is oftenreferred to as the “last mile,” or the “last underserved mile” as theseare the most challenging stages of vaccine distribution. The last mileis where the cold chain is weakest, and where immunization is mostdifficult to achieve. High-level barriers to 100% immunization revolvearound access to cold chain equipment. Where refrigerators areunavailable to store vaccines, there is a no viable way to immunizechildren. This leaves many children unimmunized or under-immunized. Insome cases, children are even “vaccinated” with vaccines that haveeither frozen or become too hot—a most egregious failure. Similarproblems arise with other pharmaceutical products such as blood,oxytocin, perishable medicines and so on.

Conventional solutions for refrigeration in the vaccine cold chain faceseveral challenges. Residential refrigerators are not viable candidatesfor vaccine storage—these refrigerators require alternating-current (AC)mains and lack precise temperature control and holdover capability(i.e., the ability to keep internal temperatures in the acceptabletemperature range during periods without power). Current WHO-approvedvaccine refrigerators that do not rely on electricity (e.g., kerosene-,gas-, and solar-based refrigerators), as a whole, tend to be expensiveand have low holdover times. Gas- or kerosene-powered absorption vaccinerefrigerators in particular are in common use, but are costly (e.g.,recurrent operating and fuel costs), challenging to maintain, and aretechnically complex, resulting in frequent failures. Many Africancountries have recently issued policies against the future purchase ofabsorption refrigerators.

Solar-powered refrigeration can be used in areas with intermittent ornon-existent electrical grid access. However, early solar-poweredsolutions have not only been expensive, but also required a rechargeablebattery. The rechargeable battery charges during sunlight hours and isnecessary to power the refrigerator when the sun is unavailable.Unfortunately, the rechargeable batteries can be costly to fix/replace,toxic, and subject to immediate failure without warning. Furthermore,some rechargeable batteries have a shorter lifetime in warmer ambientclimates—as low as five years, compared to ten to twenty years for therefrigerator it powers. Any of these issues with the battery can lead toan entire vaccine payload being spoiled.

In an attempt to remedy battery issues, Solar Direct Drive (SDD)refrigerators use a thermal battery without the need of an externalelectrical battery. Stated in another way, SDD refrigerators freezewater (or another substance) to maintain required temperature ranges inthe absence of solar power. In addition, current SDD refrigerators use avapor compression cooling system. However, SDD refrigerators are heavyand large, with payloads of about 50 L-150 L. Additionally, SDDrefrigerators are difficult to transport, and are priced beyond thereach of many communities.

As a further disadvantage, SDD refrigerators require a power surge tostart running. Therefore, while the sun may rise as early as 5 am in themorning, it may be several hours before the solar radiation is strongenough for the SDD refrigerator to turn on, thus reducing the amount ofthe solar day during which the refrigerator can run.

Reliance upon ice packs in passively-cooled ice boxes to store ortransport vaccines during outreach is an additional weakness with theexisting distribution strategy, as vaccines can freeze—rendering themineffective—when placed in close proximity to over-cooled (sub-zero) icepacks. Freezers are generally set to temperatures as low as −25 C inorder to freeze ice-packs quickly.

The WHO publishes recommended immunization schedules for diseases thatcountries should vaccinate against. New introductions to these scheduleshave included vaccines that are bulkier and more expensive (e.g.,Pneumococcal Conjugate Vaccine, Rotavirus Vaccine, Inactivated poliovaccines (IPV), and so on) that will further complicate the difficultyof last mile distribution, and the cost of vaccines that spoil due toheat or freezing.

Meeting the current and increasing demand for vaccine delivery to thebroadest possible population requires a low-cost, sustainable, durable,portable vaccine refrigerator that can be powered by solar photovoltaic(PV) panels without the complications of an external battery, without arequirement for a high startup current, and that prevents anypossibility of freezing of vaccines. Accordingly, a need exists forimproved systems and methods for thermal management and vaccine (andother such vulnerable resources) transportation in an effort to overcomethe aforementioned obstacles and deficiencies of prior art systems.

SUMMARY

In one embodiment, a refrigeration system for vaccine storage and/ortransportation includes an inner chassis. One or more vertical liftcarriages are positioned in the inner chassis and can house a pluralityof vaccines, pharmaceuticals, and/or other perishable items. Eachvertical lift carriage is contained in an isothermal chamber. One ormore isothermal chambers surround a phase change reservoir (PCR), whichis positioned at a central location of the inner chassis and containsfrozen water or another phase change material.

In some embodiments, a thermal attenuation layer is disposed between thePCR and each isothermal chamber that moderates energy transfer betweenthe chamber and the PCR, thereby controlling the temperature range ineach isothermal chamber. Surrounding the inner chassis, an additionalinsulation layer can be disposed to reduce energy transfer from theambient environment into each isothermal chamber.

The system advantageously provides for storage and transportation ofvaccines, pharmaceuticals, and/or other perishable items in the absenceof a reliable supply of electricity.

In some embodiments, the refrigerator uses at least one of solid-statethermoelectric heat pump or compact vapor compression cooling system toactively cool the PCR.

In some embodiments, the system is modular and can be scaled up or downto ensure a vaccine delivery system that is appropriate for a locationspopulation size and climatic conditions. For instance, a scaled down(e.g., backpack) vaccine delivery system allows portability to easilyservice the final steps in the cold chain described above: theDistrict/Regional Store; the Health Center; and last-mile Outreach.

In some embodiments, the vaccine storage and transport system includesapplication of data telemetry that allows electronic logging of vaccinetemperatures, refrigerator system performance, GPS coordinates (allowingtracking of any individual immunization mission), equipment/vaccineinventory, and/or immunization records/epidemiological data. Datatelemetry allows remote monitoring and control of each vaccine storageand transport system in the field. For instance, the system's power canbe controlled remotely and alerts can be sent remotely in case ofunacceptable temperatures or certain breakdowns.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary top-level block diagram illustrating a top viewof an embodiment of a refrigeration and transport system;

FIG. 2A is detail drawing illustrating an embodiment of an isothermalchamber for the system of FIG. 1, wherein the isothermal chambersupports a lift-up carriage having a variety of storage compartments;

FIG. 2B is a detail drawing illustrating an alternative embodiment ofthe isothermal chamber of FIG. 2A;

FIG. 2C is a detail drawing illustrating an alternative embodiment ofthe refrigeration and transport system of FIG. 1;

FIG. 3A is a detail drawing illustrating a perspective view of anembodiment of the inner chassis of the refrigeration and transportsystem of FIG. 1;

FIG. 3B is a detail drawing illustrating a perspective view of analternative embodiment of the inner chassis of the refrigeration andtransport system of FIG. 1;

FIG. 3C is a detail drawing illustrating a perspective view of analternative embodiment of the inner chassis of the refrigeration andtransport system of FIG. 1;

FIG. 3D is a detail drawing illustrating a perspective view of yetanother embodiment of the inner chassis of the refrigeration andtransport system of FIG. 1;

FIG. 3E is a detail drawing illustrating a perspective view of anotherembodiment of the inner chassis of the refrigeration and transportsystem of FIG. 1;

FIG. 3F is a detail drawing illustrating a perspective view of anotherembodiment of the inner chassis of the refrigeration and transportsystem of FIG. 1;

FIG. 3G is a detail drawing illustrating a perspective view of anotherembodiment of the inner chassis of the refrigeration and transportsystem of FIG. 1;

FIG. 4A is a detail drawing illustrating the inner chassis of FIG. 1including a heat pump module in accordance with one preferredembodiment;

FIG. 4B illustrates a system application of the inner chassis of FIG. 1in accordance with one embodiment of the present invention;

FIG. 4C illustrates an alternative view of the system application of theinner chassis of FIG. 4B in accordance with one embodiment of thepresent invention;

FIG. 4D illustrates a cross-sectional view of the system application ofFIG. 4B;

FIG. 4E illustrates a cross-sectional view of a system application usingan alternative active cooling system;

FIG. 5 illustrates a cross-section view of the heat pump module of FIG.4A in accordance with one embodiment of the present invention;

FIG. 6 is an exemplary top-level block diagram illustrating anembodiment of the data flow between a data acquisition and telemetrysystem that can be used with an embodiment of the refrigeration andtransport system of FIG. 1 and FIGS. 4A-E;

FIG. 7 is an exemplary top-level block diagram illustrating anembodiment of the data flow using the data acquisition and telemetrysystem of FIG. 6;

FIG. 8 is an exemplary schematic diagram illustrating an embodiment ofbackpacks that can be used with the refrigeration and transport systemof FIGS. 4A-E;

FIG. 9A is an exemplary schematic diagram illustrating an embodiment ofa carrier that can be used with the refrigeration and transport systemof FIG. 1;

FIG. 9B is an exemplary schematic diagram illustrating an alternativeembodiment of a carrier that can be used with the refrigeration andtransport system of FIG. 1; and

FIG. 9C is an exemplary schematic diagram illustrating an alternativeembodiment of a carrier that can be used with the refrigeration andtransport system of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As previously discussed, conventional vaccine storage and transportsystems are ineffective for comprehensive global distribution. Forexample, current vaccine refrigeration and transport systems adhere tothe familiar geometry of the front-opening-door refrigerator or thetravel/picnic cooler geometry with a hinged top. All of these systemsprovide operator access to a centrally located interior compartmentwhere vaccines are stored. Any thermal storage or phase change materialtypically is located around a perimeter of the interior storagecompartment. Outside of the central storage and phase change materiallining is insulation that attenuates heat flow from the environment.This geometry introduces risks of freezing vaccines and requirescomplicated controls to manage internal temperatures or the use of phasechange materials that are expensive and often do not provide the sameability to store energy as water.

If water is used in this configuration, the water cannot be allowed tofreeze, forfeiting the large thermal storage potential of water due toits heat of fusion and introducing reliance on closed loop thermalcontrol systems. Phase change materials with higher phase transitiontemperatures than water/ice are often used instead although use of suchmaterials carries a significant reduction in thermal storage capacity bymass and volume. Closed-loop thermal control systems constantly assessthe real-time refrigerator temperature and control active cooling tomanage temperatures according to user-defined settings.

Most conventional refrigerators circulate refrigerant very near to thelining of the vaccine storage chamber. Without adequate air circulation,hot spots and cold spots can emerge, creating a risk of damagingvaccines. Even with adequate circulation and/or other systems to createan acceptable internal temperature, the temperature of the chamberlining often dips or in some cases is required to be below 2° C., posinga freezing threat. Many refrigerators instruct the user to place thevaccines away from the floor and walls to prevent freezing, but usercompliance cannot be ensured. Often removable baskets are supplied withrefrigerators to keep vaccines off of the chamber floor and walls, butthis approach is prone to user misuse.

For this reason, the WHO insists upon several vaccine packaging andplacement requirements—as a precaution against freezing—that limit thedensity with which vaccines can be held, thus increasing the minimumsize storage or transport system needed to immunize a given sizepopulation. Many conventional refrigerators also suffer from lowholdover times during extended absence of power, such as at night orinadequate sunlight. Transportation options in current art (especiallyfor extended time or long distances) usually rely solely on ice packs invaccine carriers/cold boxes, which offer a limited holdover time.

Turning to FIG. 1, one preferred embodiment of a system 100 forrefrigeration and/or transport for overcoming the aforementionedobstacles is illustrated. The thermal geometry of system 100advantageously prevents freezing of vaccines as well as ensures theirviability by maintaining a predetermined temperature range (e.g., 2-8°C.). FIG. 1 shows that the system 100 can include a shell 190 forenclosing an inner chassis 110. The shell 190 can be insulated andincludes a material that can be selected based on the temperatureprofile of the intended location of use. Examples of material that canbe used with the shell 190 include, without limitation, extrudedpolystyrene (XPS), expanded polystyrene (EPS), phenolic foam, vacuuminsulated panels (VIP) (panels 410 shown in FIG. 4C), and so on.

As shown in FIG. 1, the inner chassis 110 is disposed within a cavityformed by a top opening of the shell 110. A phase change reservoir (PCR)150 is disposed at a central location within the inner chassis 110. Inone embodiment, the PCR 150 can hold water and/or other water-basedliquids. However, other phase change materials (i.e., substances with ahigh heat of fusion such that heat is absorbed or released when thesubstance changes from solid to liquid and from liquid to solid) can beused.

In some embodiments, the PCR 150 and the enclosed water (or phase changematerial) can be removed from the refrigeration system 100 to be cooledthrough an external chiller (not shown). In another embodiment, the PCR150 can include ice packs (not shown) to bring the temperature of thePCR 150 down to near 0° C. The ice packs can act as a “thermal battery,”which continue to draw energy out of one or more isothermal chambers 140for many days (even at a high ambient temperature). Additionally and/oralternatively, if water is used in the PCR 150 and is fully frozen,acceptable vaccine temperatures can be maintained for five to seven dayswithout any additional active cooling. The PCR 150 can include a singlereservoir or comprise a number of smaller reservoirs that form the PCR150.

Advantageously, keeping a core of the PCR 150 initially at a low (e.g.,0° C. or subzero) temperature allows use of high thermal storagecapacity materials (e.g., water-based PCR materials)—despite thosematerials having a lower phase change transition temperature than isnormally acceptable for vaccines—substantially reducing cost and weightwhile improving safety.

Within the inner chassis 110, the one or more isothermal chambers 140surround the PCR 150. In some embodiments, a thermal attenuation layer170 is provided between the PCR 150 and each isothermal chamber 140 tomoderate energy transfer between the PCR 150 and the isothermal chambers140. The thermal attenuation layer 170 (of which the material, size, andso on can be customized to local geo-climate conditions) between the PCR150 and the isothermal chambers 140 creates a protective insulationbetween the PCR 150 and each isothermal chamber 140, preventing storedvaccines from freezing.

The shell 190 forms a chamber around the chassis 110 and can include oneor more vacuum insulated panels 410 (e.g., shown in FIG. 4C) to providepowerful insulation from fluctuating ambient temperatures. The chambers140 advantageously can be isothermal and made from materials with a highthermal conductivity, thereby enabling a stable narrow temperature rangewithin each chamber 140 even as energy is entering the chamber 140 fromthe external environment as energy is leaving the chamber 140 to the PCR150. Stated in another way, heat reaches the isothermal chambers 140from the environment primarily on one or more sides of the chambers 140that face the exterior of the refrigerator system 100. This heat—whicharrives primarily on one or two of the four sides of the chamber—israpidly conducted around all four sides of the isothermal chamberthrough the highly conductive material so that one side is not hotterthan the other. As a result, the temperature at all points within theisothermal chambers 140 is consistent.

Each isothermal chamber 140 is configured to receive a vertical lift-upcarriage 120 (shown in FIGS. 2A-C). As the temperature is uniformthroughout the chamber 140 (in a manner that does not require aircirculation power), the vertical lift-up carriage 120 can be filledcompletely with vaccines without concern for packing the vaccines tootightly. Packing the vaccines too tightly could threaten the requiredthermal environment of vaccines in conventional refrigeration systems.

The thermal geometry of the refrigeration system 100 creates a thermalgradient between the frozen core in the PCR 150 (0° C. or lower) and theexternal environment (ambient temperatures typically are about 32-43°C.). The thermal attenuation layer 170 and the insulation in the shell190, together, moderate the flow of energy across this thermal gradient.The characteristics, such as choice of materials and thickness, of thethermal attenuation layer 170 may be influenced by the applicableambient climate as well as the size of the PCR 150 and/or the size andcapacity of the system 100. The thermal attenuation layer 170 can bemade of a suitable material including metals, open or closed cell foams,plywood, synthetic polymers, extruded polystyrene (XPS), neoprene, andso on. Plywood, for example, may be suitable for warmer climates, whileneoprene is insulating and can be suitable for use in colder climates.Furthermore, the thermal attenuation layer 170 can exist in a solid,liquid, and/or gaseous state.

By placing the isothermal chamber 140 between the appropriate thermalattenuation layer 170 and the appropriate external insulation 190, thetemperature in the isothermal chamber 140 where the vaccines are storedcan be kept constantly within an acceptable range (e.g., 2-8° C. forvaccines) even across a wide range of environmental temperatures. Therisk of accidental freezing thereby is limited.

In some embodiments, the system 100 provides proper vaccine protectionat ambient temperatures, for example, between 48° C. and 5° C. (i.e., asingle thermal attenuation layer 170 and a single insulation chamber 140in the shell 190 covers most of the regions where system 100 is used).Rather than relying on active feedback systems and control loops,fundamentals of heat transfer and material properties maintain thenarrow range of acceptable temperatures. Accordingly, the refrigerationsystem 100 preferably is an example of providing a passive coolingsystem.

Turning to FIG. 2A, the vertical lift-up carriage 120 can be removedfrom the refrigeration system 100 via an opening formed at a selectedportion of the chamber 140. Once the vertical lift-up carriage 120 israised, one or more storage compartments 130 are accessible. The storagecompartments 130 can be used to store any number and/or type of payloads(not shown). Non-limiting examples of payloads that can be used withsystem 100 include vaccines, medical consumables (e.g., oxytocin,antibiotics, and so on), other pharmaceuticals, perishable items, and soon. During continuous use, nesting the storage compartments 130 into thevertical lift-up carriage 120—accessible from the exterior of the system100—protects both the payloads from a temperature rise and the PCR 150from the heat gain associated with continuous chamber access events. Insome embodiments, the storage compartments 130 supports 0.5-60 L ofvarious payloads.

FIG. 2B illustrates an alternative embodiment of the vertical lift-upcarriage 120 of FIG. 2A, when the vertical lift-up carriage 120cooperates with the inner chassis 110. Similarly, FIG. 2C illustrates anembodiment of the inner chassis 110, wherein the inner chassis 110 isremovably disposed within the shell 190. Although shown as avertical-lift up carriage 120 that can slide vertically, otherconfigurations can be used to provide access to the storage compartments130 from the isothermal chambers 140. For example, the payload can behoused in spring-loaded tubes that can be placed upright directly in theisothermal chamber 140 and/or directly placed in the isothermal chamber140 without the need for the vertical lift-up carriage 120.

Even further, each vertical lift-up carriage 120 and/or storagecompartment 130 can house a different type of payload (e.g., food versusvaccines) and/or a group of similar payloads (e.g., all vaccines in aselected vertical lift-up carriage 120). Therefore, depending on thespecific need, the system 100 enables selective need-based access of aselected vertical-lift up carriage 120, reducing the access frequencyand minimizing heat gain into core of the system 100 during clinicevents.

Each vertical lift-up carriage 120 can maintain a predetermined numberof storage compartments 130. For example, the storage compartments 130can include trays 131A (shown in FIG. 3A) and/or drawers 131B (shown inFIG. 3B). Turning to FIG. 3A, the trays 131A can be useful for storing anumber of vaccine vials. The trays 131A can be light-weight and providehigh-density packing that is customizable at the individual tray levelfor allowing sizable populations to be immunized, for example, byhuman-scale end-of-cold-chain transport. The trays 131A prevent freezingof the individual vaccines, enabling more vaccines to be transportedwithout a need to increase system volume. Further, the storagecompartments 130 can be made of a suitable material including metal,plastic, wood, rubber, and/or any other suitable material compatiblewith the system construction.

FIG. 3B illustrates an alternative embodiment of the inner chassis 110.In this embodiment, the inner chassis 110 is similar to that shown inFIG. 3A; however, the inner chassis 110 of FIG. 3B includes drawers 131Ballowing conventional vaccine vial packing. The same payload volume canalso be used, as illustrated in FIG. 3A, with boxes of vaccines storedin the drawers 131B, which will fit single or multi-dose vial boxesefficiently just as-is, but can be removed to accommodate larger boxesas well. Although not illustrated, the vertical-lift up carriage 120 canalso include shelves upon which the vaccines and other payload can bedirectly stored or stacked in their packaging.

FIGS. 3C-G illustrate alternative embodiments of the vertical lift-upcarriage 120. Turning first to FIG. 3C, the inner chassis 110 is shownas being modular, which enables scaling in size and easy integrationwith other vaccine transportation systems that are built with similargeometry (e.g., a backpack vaccine transporter (shown in FIGS. 7-9B-C),which uses the same design and components as the inner chassis 110).Turning to FIG. 3D, the vertical lift-up carriage 120 is easily andreadily removable for minimizing heat gain into the core of the system100 during clinic events. FIG. 3E further illustrates that the tray 131Acan be densely packed at the individual tray level, without sacrificingtemperature changes, for allowing sizable populations to be immunized.

In some embodiments, the vaccine type can be presorted by tray color,tray size, and elevation in the vertical lift-up carriage 120,advantageously, helping reducing the risk of errors in immunization,while reducing the time vaccines are exposed to ambient temperatures.Vaccine vials can be prepackaged into high density trays 131A, whichthemselves nest into high density arrays, such as the arrays shown inFIG. 3F.

By using a predetermined size for the storage compartment 130, themodular trays 131A can provide flexibility (e.g., holding various sizesof single-dose and multi-dose vials and single-use syringes). Turning toFIG. 3G, the modular trays 131A can include a variety of trays 132A-C,each for receiving a different payload. For example, tray 132A includesvaccine cavities of about 14 mm in diameter for holding about sixtysmall vaccine vials. Tray 132B includes vaccine cavities of about 17 mmin diameter for holding about forty-five mid-sized vaccine vials.Similarly, tray 132C includes cavities of about 11 mm in diameter tohold about sixty single-use syringes. Advantageously, the modular trays131A can be customized by region and/or pre-packaged at the vaccinemanufacturing lab. Color-coding (or labeling) can provide a simpleidentification scheme and ease of use during clinical trials. Eachmodular tray 131A can have uniform cavity sizes and/or cavities ofvarying sizes to accommodate any number and/or type of payload stored inthe tray 131A. As shown in FIGS. 3E-G, the trays 131A can be stackableto accommodate various heights of vials.

In some embodiments, selected components in system 100 can be modular.Exemplary modular components can include: a) the vertical lift-upcarriage 120 within the isothermal chambers 140, further sub-modularizedby storage compartments 130 (e.g., vaccine vials in high density trays131A); b) PCRs 150, the sizing and number of which can determinehold-over time; and/or c) thermal attenuation layer 170. The modularityof these components allows system 100 to be scaled to fit differentregions where system 100 may be used. For example, a 10-liter payloadcapacity may be an appropriate capacity in some areas. Each of thesecomponents can be combined in a configuration that matches a selectedneed (e.g., longer or shorter hold-over times, larger or smallerpopulations to be served, storage capacity needed at any given location,distance to be traveled on foot at the end of the cold chain, etc.).This modular design also simplifies manufacturing because the same basiccomponents are used in varying combinations to build many differentproducts as needed.

As discussed above, system 100 provides an example of a passive coolingsystem. Stated in another way, the thermal geometry of system 100advantageously allows maintaining appropriate temperatures for extendedperiods without an active cooling system. An alternative embodiment ofthe system 100 can include an active cooling system. FIGS. 4A-C show thesystem 100 that includes the active cooling system. In FIG. 4A, forexample, the water (or other phase change material) in PCR 150 can becooled through the active cooling system, such as a heat pumping system160 (also optionally modular). As shown, the heat pumping system 160includes at least one (or more) thermoelectric (TE) heat pump module160A. In some embodiments, each TE heat pump module 160A can be placedon the exterior of the inner chassis 110 for easier access andmaintenance.

In an alternative embodiment, the heat pumping system 160 (e.g., thethermoelectric modules and fan as well as fluid circulating pump shownin FIG. 5) can be powered through direct DC-DC charging by a solarphotovoltaic system (not shown). The heat pumping system 160 can beconnected directly to solar panels (not shown) via a microcontroller 641(shown in FIG. 6) without the need for intermediary powerconditioning/battery storage/buffering. The solar insulation level ofthe system 100 is tracked and the input voltage is controlled by themicrocontroller 641 to regulate the function of the heat pumping system160. Instead of storing electrical energy in a battery, therefrigeration system 100 can use a thermal battery as the PCR 150 tomaintain payload temperatures within the predetermined range (2-8° C.).For example, under certain conditions such as at night or during cloudy,rainy weather, the well-insulated cool storage of system 100 maintainsacceptable temperatures for many days. Further, the use of solar powermakes the system 100 even more independent from unreliable power grids,improves portability of the system 100 and increases reliance on cleanenergy.

FIG. 5 is a detail drawing of one embodiment of the TE heat pump module160A that can be used with the system 100. Turning to FIG. 5, the TEheat pump module 160A consists of a thermoelectric module 210, a heattransfer fluid recirculation pump 220, and a heat rejection fan 230(only two moving parts). The heat transfer fluid recirculation pump 220is the innermost part of the TE heat pump 160A and couples the TE heatpump module 160A—specifically the coldest point on the TE heat pumpmodule 160A where energy is extracted—and a fluidic circuit 420 (shownin FIGS. 4B and 4D). The thermoelectric module 210 extracts energy fromthe heat transfer fluid recirculation pump 220, which chills a coolantcirculating through the heat transfer fluid recirculation pump 220.

Therefore, turning to FIG. 4B, to reduce temperature in the PCR 150, theheat pump module 160A extracts heat from the fluidic circuit 420, whichthen runs sub 0° C. liquid through the PCR 150. As shown in FIG. 4B, thefluidic circuit 420 includes an array of copper fins 421. With referenceto FIG. 4D, a cross-sectional view of the refrigeration system 100 isshown. FIG. 4D also shows the active cooling system (e.g., an array ofTE heat pump modules 160A), which can pump chilled fluid (e.g., coolant)into PCR 150 via the heat transfer fluid recirculation pump 220.Specifically, a fluidic pump tube system 422 runs along the height ofthe system 100 and connects the heat transfer fluid recirculation pump220 to the copper fins 421 in the PCR 150 at a top portion 422A.

The coolant passes along the height of system 100, through the fluidicpump tube system 422 of the fluidic circuit 420 and into the coppertubes 421 that are located inside the PCR 150. Therefore, the coolantthrough the fluidic pump tube system 422 cools the water or other phasechange material contained within the PCR 150. The TE heat pump module160A pushes energy extracted at the heat transfer fluid recirculationpump 220 through the module to the heat rejection fan 230, which thendissipates the heat into the atmosphere. Thus, the PCR 150 is broughtto, and maintained at, a temperature close to 0° C. Combined with thethermal attenuation layer 170, the PCR 150 enables the entire system 100to maintain payloads within the predetermined temperature range.

In an alternative embodiment, rather than using the fluidic circuit 420,a solid state heat extraction is used (i.e., without the need forfluid). The TE thermoelectric heat pumps 160A are situated on, or verynear to, the PCR 150. Therefore, heat extraction occurs through thewalls of the PCR 150 and/or using heat pipes (not shown) to extract heatfrom within the core of the PCR 150 without the need for fluid. A breakin the thermal pathway can be achieved by creating a physical separationbetween the cold side 240 of the TE thermoelectric heat pump 160A andthe PCR 150 when the system 100 is not actively powered. In someembodiments, the heat pump module 160A transfers this heat into theenvironment through the array of copper fins 421 and a fan (e.g., theheat rejection fan 230) at the base of the refrigerator. The heat pumpmodule 160A is configured to be easily replaceable by medical staff withminimal engineering or technical skill.

Turning back to FIG. 4B, the refrigeration system 100 is shown asincluding the inner chassis 110 having the PCR 150 at the core. FIG. 4Billustrates that the refrigeration system 100 has two PCRs 150, but therefrigeration system 100 can have any suitable number of modular PCRs150, as desired. Similarly, four isothermal chambers 140 are shown tosurround the PCRs 150. Each isothermal chamber 140 receives a verticallift-up carriage 120 that is shown to support a stack of trays 131A.

FIG. 4C shows the refrigeration system 100 with the placement of innerchassis 110 into an insulated shell 190, which can comprise vacuuminsulated panels 410 that form an opening at a top portion of the shell190 for receiving the inner chassis 110. Once received, a top accessdoor 430 can be used to access the vertical lift-up carriages 120 fromeach isothermal chamber 140.

In a preferred embodiment, the active heat pumping element 160 is aself-contained unit that can: a) include “thermal diode” properties(discussed below) to minimize standby losses; b) be replaced easily byan unskilled staff member; and/or c) be used in the quantity needed foreither high or low power systems (multiple TE heat pump modules 160Aprovide for redundancy and allow the system 100 to operate even if oneTE heat pump module 160A fails).

A low thermal resistance path can present a thermal liability when theheat pump 160 is not active. That is, the highly thermal conductivepathway that enables the heat pumps 160 to efficiently extract energywhen the refrigeration system 100 is running can also allow heat toenter the refrigeration system 100 when the refrigeration system 100 isnot running (e.g., at night). In order to minimize the standby heatlosses, to achieve a long hold-over with a practical amount of thermalstorage, the conduction path can be broken with a “thermal diode”configuration shown in the refrigeration system 100 in FIG. 4D and FIG.5. For example, TE heat pump module 160A can be physically disconnectedfrom the PCR 150. Similarly, the TE heat pump module 160A and the PCR150 can be connected through a fluidic circuit 420. While the TE heatpump module 160A can be effective at moving energy both out of thesystem (when active) and into the system (when inactive), the fluidiccircuit efficiently moves energy when the fluid is circulating. Thisway, when the system is “off” and the fluidic circuit 420 is static, thePCR 150 is isolated from the TE heat pump module 160A and its highthermal conductivity path to environmental heat.

The fluidic circuit 420 connects the cold side 240 of the TEthermoelectric heat pump 160A, the point from which energy is extracted,and the PCRs 150. Accordingly, when the refrigeration system 100 is off,there is no highly conductive path linking the external environment andthe PCR 150. The fluidic circuit 420 can be turned “off” to provide abreak in the thermal pathway between the outside environment and the PCR150.

Thermoelectric heat pumping modules advantageously enable: a) portable,rugged, reliable operation, promoting an easily repaired and modularsystem; b) light weight and solid states, using no refrigerants; c)unlike in a vapor-compression heat pump, starting does not require asurge of power, thus enabling it to run continuously, andproportionately to the magnitude of solar insulation. It is alsodesigned to couple tightly with a wide range of solar PV panel outputs.

With reference now to FIG. 4E, an alternative embodiment of therefrigeration system 100 having the active cooling system is shown.Turning to FIG. 4E, the refrigeration system 100 is shown as including avapor compression cooling system 160B. The vapor compression coolingsystem 160B includes an air cooled condenser 162, at least oneevaporator 163, and small-scale compressor 164. A refrigerant isobutane(or other) in alternating liquid and vapor form is routed through thesmall-scale compressor 164, condenser 162, capillary tubes andevaporator 163, which extracts heat from the central PCR 150. Asdiscussed above, the vapor compression cooling system 160B canalternatively be powered through direct DC-DC charging by a photovoltaicsystem. The vapor compression cooling system 160B advantageouslyprovides a smaller and lighter compressor than conventional compressorsand generates a relatively smaller power surge.

In another embodiment, data telemetry can be used to log and transmitdata from the refrigeration system 100 to a centralized location forremote monitoring. Turning to FIG. 6, using a Graphic User Interface(GUI) 610, a remote administrator can monitor data and send commands tothe refrigeration system 100. In this embodiment, a microprocessor (notshown) embedded in a controller 641 of the refrigeration system 100autonomously collects data from various sensors in the refrigerationsystem 100 (including, but not limited to, temperature sensors 642,photovoltaic (PV) array state, etc). Supercapacitors 643 with a memorycard and a display (for readings and diagnostics) connected to thecontroller 641 can record/store status information when there is nosunlight and PV source. These logs provide diagnostics as well alarms ifthe temperatures (from the temperature sensors 642 located at selectedpoints in the refrigeration system 100) go outside the predeterminedtemperature range in absence of a PV source. Additionally and/oralternatively, a local user interface (UI) 644 may be linked to thecontroller 641 and can be used to manually enter data, for example,regarding vaccine administration, vaccine inventory, immunizationrecords, etc. The controller 641, via a serial port for example,transmits the information through a cellular modem 645 (which can have aglobal positioning system (GPS) receiver for identifying location dataof the refrigeration system). Transmission infrastructure for telemetryto a centralized location (e.g., over a data network 630 such as viacloud computing) allows for remote monitoring, early alerts, early faultdetection, and early response to any anomalies.

A backend data processor 620 can also perform analytics and be used tosend commands to the refrigeration system 100 via the same bidirectionaltransmission channel (e.g., over data network 630). The GUI 610 allowsthe remote administrator to monitor and manage the controls of therefrigeration system 100. On the end of the refrigeration system 100,the commands are received by the controller 641, which in turn controlsvarious refrigeration system 100 functions 646, including the powerconvertors, heat pumps and fan function in the refrigeration system 100.In some embodiments, the power convertors, heat pumps, and fan functionsin the refrigeration system 100 are modular and their number can beselected depending on the capacity of the refrigeration system 100.

Data collection and telemetry of vaccine payload temperatures, systemperformance, physical location, and vaccine payload access profileenables remote monitoring of broadly distributed fleets of vaccinerefrigerators and vaccine backpacks to ensure the most successfulvaccine campaigns as possible (shown in FIG. 7).

As an additional advantage, the refrigeration system 100 are much moreaffordable to a much wider population base than competing alternativesand are able to store vaccine vials at off-grid locations in the vaccinecold chain for extended periods. For example, in an 18 L version, therefrigeration system 100 can maintain thermal stability for about fivedays without requiring external power, such as solar or grid power. Theability to reliably hold thermally-protected vaccines at such locationsfor weeks or months on solar power can fundamentally change immunizationcampaigns in areas that could previously only provide occasional andvery time-limited clinics for immunization.

FIGS. 9A-C illustrates alternative embodiments for the refrigerationsystem 100. As shown in FIG. 9B, for example, the refrigeration system100 can be disposed in a conventional carrier, such as an ergonomic,form-fitting backpack vaccine transporter 920, designed specifically foroutreach. In one embodiment, the backpack vaccine transporter 920 usesthe modular, scaled down “passive” thermal geometry components. As shownin FIG. 9C, a universal backpack 930 is equipped with standard ice packswithout the need for the PCR 150, offering the additional advantages ofcost and wide accessibility, while still preventing freezing ofvaccines. A cooler box 910 is shown in FIG. 9A, which houses an innerchassis 110 and provides for ease of transportability (e.g., wheels,handles, modular PCR 150, and so on).

In an alternative embodiment shown in FIG. 8, active cooling (TE orvapor compression based) can additionally be used in a backpack vaccinetransporter similar to the backpack vaccine transporter 920.

Advantageously, the carrier configurations (shown in FIGS. 8 and 9A-C)allow compatibility with the inner chassis 110 in the refrigerationsystem 100 for easy transfer and exchange of vaccine carriages, whichaids last-mile outreach, longer holdover times than the current art, andthe increased portability allowing greater outreach to rural areas.

The following are some of the additional advantages of the refrigerationsystem 100.

It allows vaccine delivery and outreach to regions with unreliable or nogrid power with an easily transported, lower capital cost system than iscurrently available.

Its modular system design allows country/region-specific optimizationfor: a) vaccine capacity; b) holdover time; c) ambient temperature rangevariation; and/or d) serving population size; e) compatibility betweenhigher and lower capacity units.

Its active heat pump elements include “thermal diode” characteristics tominimize stand-by heat losses, as well as provide unitized, easilyserviced “Plug and Play” modules that can be accessed at the exterior ofthe refrigerator/backpack by unskilled staff.

Holdover time in this system exceeds WHO minimum requirement of 20 hoursover 3 days in ambient temperature ranges of ˜32-43° C. ambient.

It is lightweight and can be moved by an average-sized transporter,carried by two averaged-sized transporters, and easily transported bybicycle or motorcycle.

It has high fault-tolerance, with minimal and easily replaced mechanicalparts, modular heat pump redundancy and ease of repair by a healthworker with minimal training.

It is designed to be shock resistant and durable, with an expected 10years life span, and therefore quite robust.

It utilizes green technology, inasmuch as solid state cooling does notrequire refrigerants, “thermal battery” core is a phase change systemusing simple non-toxic materials and no batteries are required otherthan those for data logging (i.e., low power, non-critical).

It allows continuous vaccine vial temperature monitoring, with regularreporting via data telemetry (in locations where infrastructure enablesthis feature). In an alternative embodiment, labeling/tracking ofindividual vaccine vials can also be integrated.

Other industries that might use the refrigeration system 100 include,but are not limited to, medical equipment manufacturers in developednations—the system 100 could be useful also in high-resource countries,particularly as a transport unit—as well as otherpharmacological/biological products refrigerator manufacturers (e.g.,for blood samples, oxytocin, serums, organs for transplantation, etc.).

The language used to disclose various embodiments describes, but shouldnot limit, the scope of the claims. For example, in the precedingdescription, for purposes of clarity and conciseness of the description,not all of the numerous components shown in the schematic are described.The numerous components are shown in the drawings to provide a person ofordinary skill in the art a thorough enabling disclosure of thedisclosed embodiments. The operation of many of the components would beunderstood and apparent to one skilled in the art. Similarly, the readeris to understand that the specific ordering and combination of processactions described is merely illustrative, and the disclosure may beperformed using different or additional process actions, or a differentcombination of process actions.

Each of the additional features and teachings disclosed herein can beutilized separately or in conjunction with other features and teachingsto provide a solar powered storage and transport system. Representativeexamples using many of these additional features and teachings, bothseparately and in combination, are described in further detail withreference to the attached drawings. This detailed description is merelyintended for illustration purposes to teach a person of skill in the artfurther details for practicing preferred aspects of the presentteachings and is not intended to limit the scope of the claims.Therefore, combinations of features disclosed in the detaileddescription may not be necessary to practice the teachings in thebroadest sense, and are instead taught merely to describe particularlyrepresentative examples of the present disclosure. Additionally andobviously, features may be added or subtracted as desired withoutdeparting from the broader spirit and scope of the disclosure.Accordingly, the disclosure is not to be restricted except in light ofthe attached claims and their equivalents.

The described embodiments are susceptible to various modifications andalternative forms, and specific examples thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the described embodiments are not to belimited to the particular forms or methods disclosed, but to thecontrary, the present disclosure is to cover all modifications,equivalents, and alternatives.

What is claimed is:
 1. A system for refrigeration of a payload,comprising: an inner chassis removably disposed within an insulatedouter shell; a phase change reservoir centrally positioned within saidinner chassis; an isothermal chamber disposed around said central phasechange reservoir and for cooperating with a storage compartment forreceiving the payload; and a thermal attenuation layer disposed betweensaid central phase change reservoir and said isothermal chamber and fordefining a payload temperature range.
 2. The system of claim 1, furthercomprising an active cooling engine coupled to said inner chassis anddisposed on an external opening formed by the insulated outer shell. 3.The system of claim 2, wherein said active cooling engine comprises atleast one of a thermoelectric heat pump and a vapor compression coolingsystem.
 4. The system of claim 3, wherein said at least one of saidthermoelectric heat pump and said vapor compression cooling system usesat least one of fluidics-based or solid-state cooling.
 5. The system ofclaim 1, further comprising a control system coupled to the insulatedouter shell for communicating electronic data related to metrics of thesystem to a central server over a data network.
 6. The system of claim5, wherein the electronic data comprises at least one of global positioninformation of the system, temperature of the system, payload inventoryof the system, and payload administration of the system.
 7. The systemof claim 1, further comprising a vertical lift-up carriage housing saidstorage compartment, wherein said isothermal chamber receives saidvertical lift-up carriage.
 8. The system of claim 1, wherein saidinsulated outer shell comprises at least one of a cooler system and abackpack system.
 9. The system of claim 1, wherein the insulated outershell is formed from at least one of extruded polystyrene (XPS),expanded polystyrene (EPS), phenolic foam, and vacuum insulated panels(VIP).
 10. The system of claim 1, wherein said phase change reservoirholds at least one of water, a water-based liquid, and a phase changematerial.
 11. The system of claim 1, wherein said storage compartmentincludes at least one pull-out tray, at least one shelf, and at leastone drawer for enhanced density of payload packing.
 12. The system ofclaim 11, wherein said pull-out tray, said shelf, and said drawercomprise at least one of metal, plastic, rubber, and wood.
 13. Thesystem of claim 1, wherein said payload temperature range comprises atemperature range of 2-8° C.
 14. The system of claim 1, wherein at leastone of said phase change reservoir, said isothermal chamber, saidthermal attenuation layer, and said storage compartment is modular. 15.The system of claim 1, wherein said thermal attenuation layer includesat least one insulating material selected from the group comprising ametal, an open or closed cell foam, plywood, a synthetic polymer,extruded polystyrene (XPS), and neoprene.
 16. The system of claim 1,wherein said payload comprises at least one of a vaccine, a medicalconsumable, a pharmaceutical, and a perishable item.
 17. A method forproviding a system for refrigeration of a payload, comprising: removablydisposing an inner chassis within an insulated outer shell; centrallypositioning a phase change reservoir within said inner chassis;disposing an isothermal chamber around said central phase changereservoir, said isothermal chamber cooperating with a storagecompartment for receiving the payload; and disposing a thermalattenuation layer between said central phase change reservoir and saidisothermal chamber for defining a payload temperature range.
 18. Themethod of claim 17, further comprising coupling an active cooling engineto said inner chassis, wherein the active cooling engine is exposedthrough an external opening formed by the insulated outer shell.
 19. Themethod of claim 18, wherein said coupling the active cooling enginecomprises coupling at least one of a thermoelectric heat pump and avapor compression cooling system.
 20. The method of claim 18, furthercomprising charging said active cooling engine using a solarphotovoltaic system coupled to said inner chassis.
 21. The method ofclaim 17, further comprising coupling a control system to the insulatedouter shell for communicating electronic data to a central server over adata network.
 22. The method of claim 21, wherein said communicatingelectronic data comprises communicating at least one of global positioninformation, temperature of the system, payload inventory, and payloadadministration.
 23. The method of claim 17, further comprising disposingsaid storage compartment in a vertical lift-up carriage, and disposingsaid vertical lift-up carriage in said isothermal chamber.
 24. Themethod of claim 17, wherein said removably disposing said inner chassiswithin said insulated outer shell comprises removably disposing saidinner chassis in at least one of a cooler system and a backpack system.25. The method of claim 17, wherein the insulated outer shell is formedfrom at least one of extruded polystyrene (XPS), expanded polystyrene(EPS), phenolic foam, and vacuum insulated panels (VIP).
 26. The methodof claim 17, further comprising filling said phase change reservoir withat least one of water, a water-based liquid, and a phase changematerial.
 27. The method of claim 17, wherein said storage compartmentincludes at least one pull-out tray, at least one shelf, and at leastone drawer for enhanced density of payload packing.
 28. The method ofclaim 27, wherein said pull-out tray, said shelf, and said drawercomprise at least one of metal, plastic, rubber, and wood.
 29. Themethod of claim 17, wherein said defining the payload temperature rangecomprises defining a temperature range of 2-8° C.
 30. The method ofclaim 17, wherein at least one of said phase change reservoir, saidisothermal chamber, said thermal attenuation layer, and said storagecompartment is modular.
 31. The method of claim 17, wherein saiddisposing the thermal attenuation layer includes disposing at least oneof a metal, an open or closed cell foam, plywood, a synthetic polymer,extruded polystyrene (XPS), and neoprene.
 32. The method of claim 17,wherein said payload comprises at least one of a vaccine, a medicalconsumable, a pharmaceutical, and a perishable item.
 33. A system forrefrigeration of a payload, comprising: an inner chassis removablydisposed within an insulated outer shell; an ice pack centrallypositioned within said inner chassis; a isothermal chamber disposedaround said ice pack and for cooperating with a storage compartment forreceiving the payload; and a thermal attenuation layer disposed betweensaid ice pack and said isothermal chamber and for defining a payloadtemperature range.